The present invention relates to a tiltable arc furnace having a closable discharge opening in the bottom of a projecting bay-like part of the furnace vessel.
A furnace of the type to which the invention pertains is, for example, shown in German printed patent application 18 04 007. The construction chosen has the purpose of reducing the tilt angle of the receiving vessel during discharge of the furnace vessel. The conventional furnace construction with discharge spout requires the vessel to be lifted relatively high which in turn requires movement of considerable weight. In the example illustrated in FIG. 2 of the above identified publication, the tilt angle of the furnace is about 30.degree. to 40.degree..
the known furnace vessel as disclosed in the above identified German printed patent application exhibits a considerable level distance between the bay-like vessel part and the remaining bottom portion of that vessel. The same conditions prevail in the British patent 622,500. The German printed patent 29 44 269 does likewise show a particular bottom portion with discharge opening being situated considerably higher than the remaining vessel bottom. As a consequence of this kind of arrangement there will always be thin layer of molten metal to be discharged and being situated above the opening during the discharge procedure. This is true in spite of the still relatively large tilting angle. It was found in practice that eddys are formed within this thin metal layer and part of the slag is sucked into the eddy and discharged with the molten metal. This is turn deteriorates the quality of the discharged material.
In addition to the drawbacks outlined above, the known furnaces with a bay-like portion of the vessel with discharge opening are endowed with another considerable drawback: the discharge openings are usually closable by means of plugs which are situated within the vessel and are operated by means of rods which generally project in upward direction. Therefore, such a plug as well as the respective actuating rod are immediately exposed to the molted metal. Consequently, both the rod and the plug exhibit considerable wear. Maintenance of these parts is difficult because, as stated, the rod is run within the vessel and the plug is likewise situated therein. German printed patent application 29 44 269 attempted to covercome the problems of plug actuation by using a floating arrangement wherein the closing element floats on top of the metal bath. However, in view of the turbulence in the zone of the discharge opening, the desired and requisite separation of metal from slag was not achieved.